Linkage for artificial legs



G. G. HAVENS LINKAGE FOR ARTIFICIAL LEGS Oct. 5, 1948.

2 Sheets-Sheet 1 Filed July 26, 1947 nventor /enn Ha vens Tim@ Md?Gttorne 06f. 5, 1948 I G, G, HAvENs 2,450,728

LINKAG-E FOR ARTIFICIAL LEGS Filed July 26, 1947 2 sheets-Sheet 2Snventor /enn Ha vens E twpwluv Ctttorneg Patented Oct. 5, 1948 UNITED`SfltfIiE;S PA'TFiENTA OFFICE .LINKAGEFDR ARTIFICIAL LEGS Glenn G'.Havensys'an Diego, Calif.,- assignor to Consolidated VulteefAix-craftCorporation, San fDiege, Calif., al corporationvfoi'- DelawareApplicationiJulyZG, 1947, Serial N0. 763,924

1:3. Claims.

This invention relates to improvements Iin pros-l theses and moreparticularly to improvements in linkages tor prostheses.

The invention will be .iil'ustrated as utilized i-n con-junction withan.. artificial leg but `it is, of course, conceivable that it could beincorporated in other types of prostheses. In the past,-many attemptshave been madeto provide-artifrcial-legs which would simulate theappearance and action of a normal. leg but theyl have not beenl toosuccessiul. In the -firstplace vthe-actuation offprior art legshasdepended, to `a large extent, onv complicated and cumbersomearrangements of strapsalnd cables which are tted to the body of thewearer of the leg and which hev must control l.by movements of his-bodyto cause the leg to functionp-roperly. Such bodilyl movements result inan unnatural appearance'in the stride 0i the wearer and the-leg does notimpart the easy, normalmovernent-whichit is d'esiredrto achieve.

Inacl'dition, such legsV frequently have embodied thereinmechanical-locking and -clutchmechanismswhich-areadaptedboth to controlthe-movements of thefleg-and prevent the leg' from break-` ing at thekneejoint when'the weight-ofthe wearer is imposed upon therleg..vTypicalznfieclianism's. of this type are Ausuallycumbersome and vheavyand create a certain amount .ci noisefwhen the leg is in motion.Naturally, noise -oi thisftype substantially derogates from thepsychological security of' the individual wearing the leg.

Gif. course, the greater thev complexity of conventional prosthesislinkages the---greater 'the amount of time andfmoney that lmus-t beVexpended inthe maintenance of themY in properfunction-l ing conditi-on.i It is desirablethat 1 expenditures for mai-ntenanceand repair -bereduced v.to aminimam since individualswho must utilizek such prosthesesare frequently those who canleast afford theV costof such. upkeep.Naturally, if any major repairs-mustzbe made .and theleg kepty out oi;use for a con-s-iderabletime, rit will necessitate the inactivityoff theowner-oithe-leg.

Conventionalprostheses are -so designed, and.

=Direct mechanical linkages embodied conventional prostheses permit onlystraight', line movement Voi the leg fand recent analyses of nor-a.

mal leg movementsl have shown that, in addition to axial twisting of thethigh and shank structure, ankle movements embracefa considerable amountof plantarlexion and dorsiflexion or a combinationv of both. I nthepast, no attempthas-:been made to achieve the'sirnulation' oiactualmovements of thi'stype in artificial limbsv and thus; it

l hasibeenimpossible for the wearer oiconventiona limbs to simulate anormal gait.

As indicated above, the maintenanceand repair problems encountered inthe use of conventional prosthesis linkagesV are apt to bea'la'r'gefiactor in the expense of' such'd'evices since no provisionscloses linkage meansy for prostheses and locking means adaptedtocontrollsaid linkage means, means adapted tosecure said shank tosaidlink-4 ages in such a ,manner thatvsaid shank may .be

readily removed from said linkages' to` permit-the' removal of saidlinkages for repair or replacement orito replace anew shank for usewithsaid linkages.y l

Itis, therefore-an .object .-of the .present .invention; to .provide :ailinkage Afor the structural7 components-z of-1an artificial legwhichwillserve to actuate the leg. vwithoutnthe use' of conventional body strapsor elaborate;mechanismsembodied withinathe legitseli. y Y

Anotherobject of the present` inventionfis' the provision an, articialleg of :locking means adapted, when the weight ofr the -wearerisimposedonltheleg;y to cause the leg vto beiv locked-'and when' theweightof the wearer is removed from the' leg to cause it to'fbevunlocked by' permitting the' longitudinal `displacement of one of thecompo; nents of' ,the joint inv which saidlocking meansr is incorporatedin relation to the, other;

AA further object oi the pr'esentinvention is the"Y ,fprovision'oflinkages forv an articial limbwh'ich are so designed and constructedthat no noise is generated when the limb is in motion.

An additional object of the present invention is the provision oflinkages for an artificial limb which are simple in construction, cheapto manufacture and which can be readily removed for replacement whenworn out or damaged.

Another object of the present invention is the provision of linkages foran artiiicial leg which are capable of absorbing shock and impact loadsand which prevent a large portion of such loads from being transmittedthrough the leg into the stump of the wearer.

A further object of the present invention is the provision of anartificial leg having embodied therein locking means adapted to limitthe lateral displacement of the shin portion of the leg in relation tothe thigh portion of the leg.

An additional object of the present invention is the provision in anartificial leg of linkages which permit the limited rotation of theshank ofthe leg about its vertical axis and which also permit theplantariiexion or dorsifiexion of the ankle or the combined dorsiilexionand plantariiexion of the ankle. v

4 Other objects and advantages of the-present invention will becomeapparent when the appended specification is read in conjunction with theaccompanying drawings, in which:

Figure 1 is a .vertical sectional View of an artiicial leg havingembodied therein a knee joint incorporating linkages exemplifying thepresent in-x vention;

Figure 2 is a vertical sectional View taken online II-II of Figure 1 andshowing the knee jointV linkages con-structed in conformity with thepresent invention;

Figure 3 is a transverse sectional View taken on line III-III of Figure1';

Y Figure 4 is aV detailed sectional View of a linkage constructed inaccordance with the present invention;

n ,Figure 5 is a vertical sectional View of an ankle constructionembodying linkages constructed in accordance with the present invention;

Figure 6 is avertical sectional view taken on line VI-VI of Figure 5;

` 'Figure 7 is a side elevational View showing the stop and mountingmeans associated with the ankle joint linkages; and

`'Figure 8 is a front view, partly in elevation and partly in section,showing the manner of mounting the ankle linkages in the lower end ofthe shank assembly of an artificial leg.

f There is shown in the Vdrawings (Figure 1) a portion of an artiiicialleg I showing a thigh section il and a shank section I2 adapted to beconnected to each other through the intermediary of linkage orconnecting elements I3. The construction of thigh and shank sections IIand I2 is not the subject of the present invention but since it isnecessary that the linkage or connecting elements I3 be connected toboth of these sec tions the basic structure will Ybe briefly disclosed.As` indicated above, the structure of the shank is fully disclosed inco-pending application, Serial No. 750,504 filed May 26, 1947.

The shank section I2 of the leg Ill is composed of a centrally disposed,weight bearing, tubular column I4 which has disposed thereabouta fairingcomprised of a multiplicity of vslabs or layers I of plastic foamsuperimposed one upon the other and adapted to impart a symmetricalconfiguration to the exterior shell of the shank.

The symmetrical conguration of the leg is achieved by so forming theblocks that their peripheries cooperate to achieve the outline of anormal leg. The exterior shell of the shank includes a plastic skin I6which is secured to the peripheries of the slabs I5 by an appropriateadhesive and then cured in position. The central, weight bearing columnI4 and the skin I6 are both formed -from a low-pressure plasticimpregnated laminatev which comprises an appropriate ller impregnatedwith a thermosetting resin. The skin I 6 is covered by a combination ofrubber and plastic elements adapted to impart life-like visual andtactual qualities to the leg. Thigh section II is of fundamentallysimilar construction to shank section I2 but no central bearing columnis utilized. A stump socket Il formed of a low-pressure plasticimpregnated laminate is mounted within a shell I8 of similar materialand ysurrounded by a bed of compressed brous material. Although allusionis made to the utilization of specific materials in the construction ofthe invention it is, of course, not intended that it be constructed onlyof these materials but only to indicate that they are preferred.

Secured to the lower end of the shell I8 is a plate I9 having formedtherein a plurality of arcuate, V-shaped, depending elements 2U whichare reinforced by a packing of fibrous material similar to thatinterposed between stump socket Il and shell I 8. Plate IB is formed outof a lowpressure plastic impregnated laminate. Associated with plate I9and adapted to act in cooperation therewith is a semi-cylindrical blockor sheave 2l having flat sides 22 and a cylindrical depending neck orcollar 23. The block 2l is formed of a low-pressure plastic impregnatedlaminate and has formed in the upper surface thereof a plurality ofarcuate V-grooves 2li adapted to receive the V-shaped depending elements20 in a cooperative relationship. Emhraced Within the interior of theblock 2| is a reinforcing core 25 of maple or similar hardwood whichserves to prevent the collapse of the cylindrical block 2I when crushingloads are imposed thereupon.

. Thigh section II and shank section I2 are joined together through theintermediary of resilient, deformable link or connecting elements I3which comprise opposed frusto-conical mounting or bearing plates 25having embraced therebetween annular discs 2'! of rubber or-similarresilient material having frusto-concave side walls adapted to receivethe frusto-conical projecting portions of bearing plates 26.

In the particular application shown the iiat sides of the opposedfrusto-conical bearing members 26 are secured to the interior walls ofshell I8 and the iiat side walls 22 of cylindrical block 2l, as bybonding with an appropriate cement or similar substance.

The depending neck 23 of block 2I is adapted to be slipped over theupper end of tubular member i 4 and nts within an expanded bore 28formed by enlarged holes formed in the center of slabs I5. Insertedwithin the upper end of tubular member I4 is a reinforcing block 29 ofhardwood or similar'material which is bonded to the interior of thetubular member and which resists crushing loads which might possiblycause the upper end of the tubular column I 4 to collapse.

' The neck 23 of block or sheave 2i is secured to the upper end oftubular column I ll by fusible thermoplastic cement which will permitthe sheave 2l to be removably secured to the top of the tubular memberI4. Thus, should the andere block or s'heaveA 2 I show-signent: wear.'or should. it be necessary to remove tubular member Lufer' any reasonfrom its connection with ztheblock 2|- the assembly .is `.placed in.amod'era'tely .hot ovenand the bond'between'.. neckj23i; and column.llt. iss fusedor dissolved.r .i However,..-in order to: secure thewearer ofthe leg.. againstpossible failure of the bond. between .the.twowmembers av throughboltzl) passes. through fthe-walls of both. theneck 23 of blockx2l` and 'the kwall vofr tubularLmember; l 4. :Italsoopassesl through .har-.clwood. block 29 and secures it againstinadvertent dislocation within columnr I4. Anaccesslio'lel` isformed.through vone. of lthe slabs. vI 5; .to .permit access to .the through`bolt 30. togpermit .the re'- moval or insertion ofthe through bolt.

When the wearery ofthe lleg -imposes this weight upon the tubular columnI4 it is forcediupwards and carries the; associated. cylindrical sheaveor block 2l upwards with it. ment -of tubular.` columnV I4 andIcylindrical block 2l ispermitted by theideflection: of thelinks or'connecting elements I 3- since the; -frusto-conical members 26 mountedIon. eitherside 22 of block ZI will `be driven upward. whiley the lweightof the wearer will tendI to carry the frusto-conical members 26 affixed'to the-walls of the shellV I8 downwards. The resilient discs 21 willthus be placed in shear. and the thigh section II and shank section I2will be carried toward. each other until the V-shapedelements 20. areforcedv into thelV-grooves 24- in the: upper surface of theblock 21|.The V-grooves 2li,v in cooperation with V-shaped elements 20 rservetolock the leg in its extended position and theknee joint cannot bebroken until the weight of the wearer is removed therefrom. When the:wearer of the leg removes his weight from it the Vf-shaped-elementsuZIlare lifted out of V-grooves24. by the return of the links I 3Y to theirunloaded positions. Also, the locking of the pluralityofV-shapedelements-1 20 in the plurality of V-grooves- Zdvprevents theimposition of a greater load-upon the resilient joints than they aredesigned to bear since the` mating of V-shaped elements 20 andV-grooves. 2,4 limitsv the extent of the longitudinal movement betweenthe shankand thigh section. The' previsioni of a plurality of V-groovesand` V-shaped, elements also serves to prevent the lateralbendi-ng ofVthe shank I2 when itis in the locked position by providing a broadbaseupon whichfthe thigh section is locked. to the shanksectiongof thelleg..1

When the weight of the: wearer is removed from theleg by the liftingofthe foot yfrom the ground the resilient connectors or links I3Yreturnto their unstressed position, moving shank section I2 away from thighsection: II.l and lwitl-idrawing' V-grooves 24. from contact withV-shaped elements. 2B. The lock on. the knee joint is thus released and.the resilient links I3 then return to their. original unloaded; positionby carryingthey shank I2 backward until it assumesa normally bentposition and raises the foot of the leg ol the ground. When the wearercomes tolthat part of his stride in whichheisready to impose his weightupon the artificial leghe swings thefleg forward on hisstump. Theforward impetus imparteci to the .shank I2.. by the. forward. swingingof the entire. leg causes thev shank I2 to be straightened.underthethighsection I.I and permits theweightof the wearer .to be-borne thereupon.When the weightof the weareris imposed o n'the leg the V-shaped.elements 20a are forced into the V-.grooves 2E andcausethe.kn.l=.e..j.0inttoA be lockedby the weight .of thewearer.

As .isf:welrknowmconsiderableshock loads` are' sustained. bythe.'normal.V foot and leg structure offlltheaverage .person.ashes-:Walks YHowever; these-loads. are absorbed and..` cancelled.'`out* by thefmusculature.landebone. structure of a normali leg. Inconventional artificial legs.;'Ahowever...'the linkages. or connectionsbetween the: several:` porcient transmitteraof .the shock loads throughthe various sections' of the' leginto .the stumpof the wearer.The'character-of the stump .naturally makesthe imposition. of f suchloads critical in: the., extreme andtan unnatural gait .results sincethewearer .tends to use :hisa artificial leg insu'ch armar-mer.. as .toplace as light a load upon-'it as possible.

In .the knee -joint construction which'nis thersubji'ect .of thevpresent invention. the embodiment, ofi resilient. A'links :I=3thereintprovides :shock absorbh4 ing'Y .characteristics .which serve to:eliminate. or" absorb. the. lgreater portion of the shock before itis.transmitted intcrthe stumpaitself. .Thelongitudi'nal transl-ation;Y ofthe shank I2. andthigh y.I I in. relationshipffto each other andascontrolledA y byiresilientflinksorconnectors I 3'A constitutes one? ofthe :major: advantages of. thisxt-ypeiV of. .construce tionin' that it.permits.'y the amputeeto .use :the leg withoutdiscomfort or hesitancy.

3R/scent. investigation of `.walking patterns has: revealed ythat :thereis. ai: certain amountof 'exii bility/in .al-:normal kneewjont`.which.permits .zal limited-. amountof. twisting of the shank of the?.leglalon'gi itsvertical: axis. -As-i thevl shank I2 of' .leg ofthepresentainvention .is thrown for-y ward theresilientl links.Ifzlpermit a; certain.

. is .essentiallyjsimilanin construction Yto that usedin.the;kneefjointdescribed above is incorporated` in'the-.ankle; jnintA33;.A can be seenfrom the drawing (Figura 52),; thel lower :zendofltubular' columnY AIll-.proiects below thel lowermost slab I5.Thereiisislippedr overthe` lower end of the tubularY member I'll` atubular'iconnector -34 which, as `it extends into the structure of;v thearticial foot.4

3,5.; is neckedI down tou provide: an elongatefsflatqsided..dependingxmemberr 36' having an arcuate; lower-end,y uponrwhich theartificial foot 3511sV adapted tobewmounted..through'thegin-termediaryofli-nks 32. l l

.Y Artiicialefoot' has formed therein. agcentral. wellySl.-wlri-iclifis;adaptedtoreceive t-he-y elo ngated.1v low-.er` end-..3t 'oftubul.ra-rfelementv 34. Fastened totubular column lili-and.securedAabout, the ex-l terior of tubularv elementyfdis: a sleeve-@Shaving itsllcgwerl portion flared out into.' a flangev onskirt 3S..Located;within;v the interi-onof tubular. colf umn lill:v a-twthe.point-A where tubular member,

and sleeve` 38x are. joined to .the tubular column` misa cylindricalblock ittici nardwoodor similar' material. adaptedy fto, act as; areinforcing.v agency I tomesist compressiye'gloads which are placedupon;

1 le.; tubular. membranes and. sieevarse .tc-1 insure terior structure'which 7 that they are retained in a predetermined location to eachother. Room is made for the expanded section created by the mounting oftubular member 34 and sleeve 38 about the lower end of tubular columnldby cutting an enlarged bore in the slabs l5.

The basic structure of foot 35, which is not a part of the presentinvention but which is briefly described here for purposes of clarity,is disclosed in co-pending application, Serial No. 773,257 filedSeptember l0, 1947. The foot 35 includes an inis composed largely ofblocks 42 of balsa vor similar lightweight material so positioned thatthe loads sustained by them are carried along the grain or" thematerial. The blocks 42 of balsa are secured together by means of strips43 of plastic impregnated laminate which also project into central well3l in foot 35 and which serve as liners therefor; Secured to the plasticimpregnated strips 43 which line the sides of central well 3l aretrapezoidal mounting plates e4 formed of the same material and Vbondedto strips 43. These plates are secured to the structure of theY foot attheir top portions by means of fasteners 45 and at their lower portionsthey have pins 46 running therethrough which have mounted thereuponspacer-sleeves d1 which are adapted to reinforce the well structure andwhich also prevent mounting plates d4 from being torn from the walls ofthe well 3l. Bonded to mounting plates 434 on either side of well 3l arefrusto-conical mounting or bearing plates or elements 48 which aredesigned to cooperate with similar frustoconicalV metallic elements 48bonded to the side walls of elongated portion 3S of tubular element 34.Positioned between the cooperating metallic elements t8 and vulcanizedor otherwise securely bonded thereto are annular discs 49 of rubber orother resilient material :embodying similar characteristics and havingformed in their oppos-itely located sides lconcavities D adapted toreceive the convexities 5! of metallic elements 48,

When the wearer of the artificial leg imposes his foot on the ground thefoot is adapted to r0- tate in both a fore-and-aft direction uponmember34 through the intermediary of the resilientY links 32 which impartsuiicient spring to the foot to Y'permit the simulation of a normalstride. To control the range through which the foot 35 will rotate uponthe elongate portion 3B of member 34, sleeve 38 and its flared out skirtportion 39 are utilized as a stop. Thus when the foot is in a state ofplantarexion, as it is leaving the ground, the rea-r portion of theskirt 3S impinges on the area bordering the rear of the central well 3lof foot 35 and prevents a further deflection of the foot. In the caseofdorsilexion, the upward tilting of the forward portion of the foot islimited by the impingement of the forward portion of skirt 35i upon thearea of the foot bounding the forward wall of the well 3l. In thismanner the rotation of the foot is confined within predetermined limitsbased upon the size and stride of the wearer and incorporated in theshape of the skirt 39. There is thu-s provided a linkage between thevarious sections of an articial leg which is simple in construction andmode of operation and which imparts to the leg verisimilitude ofactuation.

The above embodiment of the invention has been described to illustratethe details of construction and mode of operation of the invention andit is not intended to limit the invention to the details thereof, sincethe limitations of the invention are Vfully delineated in the appendedclaims.

I claim:

1. A linkage for joining one portion of an artificial leg ,to anotherportion comprising a mounting element secured to the one portion, amounting element secured to the other portion, a disc of resilientmaterial interposed between the opposite faces of said mounting elementsand securely bonded thereto to connect the one portion of said leg tothe other portion of said leg.

2. A linkage for joining the shank portion to the thigh portion of anarticial leg comprising a mounting element secured to the lower end ofsaid thigh portion, a mounting element secured to the upper end of saidshank portion and a discV of resilient material bonded to the opposedsurfaces of said mounting elements and adapted to secure them inoperable relationship to each other.'

3. A linkage for joining one portion of an artificial leg to anotherportion comprising a cylindrical mounting element secured to the oneportion, a cylindrical mounting element secured to the other portion andan annular disc of resilient material interposed between the opposedfaces of-vsai'd cylindrical mounting elements and adapted to Yjoin themtogether, thus joining said one member to said other member in operativerelationship thereto.

4. A linkage for joining one portion of an artificial legrto anotherportion, said one portion having an end thereof penetrating into theother portion, mounting elements secured to both sides of said oneportion where it penetrates into said other portion, mounting elementssecured to the interior of said other portion contiguous to the mountingelements on said one portion and discs of resilient material interposedbetween said pairs of opposed mounting elements and bonded thereto toform connector means adapted to secure said one portion of said leg tosaid other portion.

5. A linkage for joining one portion of an artiiicial leg to anotherportion, said one portion having an end thereof penetrating into theother portion, cylindrical mounting elements secured to both sides ofsaid one portion where it penetrates into said other portion,cylindrical mounting elements secured to the interior of said otherportion contiguous to theV cylindrical mounting elements en said oneportion and annular discs of resilient material interposed between pairsof opposed cylindrical mounting elements and bonded thereto to formconnector means adapted to secure the said one portion of said leg tosaid other portion.

6. A linkage for joining one portion of an articial leg to anotherportion comprising. a cylindrical frusto-conical mounting elementsecured to thev one portion, a cylindrical, frusto-conical mountingelement secured to the other portion, an annular concave disc ofresilient material interposed between the opposed frusto-conical facesof` said mounting elements and bonded thereto to join said one member tosaid other member in operative relationship thereto.

7. A linkage for joining one portion of an articial leg to anotherportion, said one portion having an end thereof penetrating into theother portion comprising, cylindrical, truste-conical mounting elementssecured to both sides of the one portion whereit penetrates into saidother portion, cylindrical, truste-conical mounting elements secured tothe interior of said other portion contiguous `to the cylindrical,frusto-conical mounting elements on said one portion and annular discsof resilient material, having concave sides adapted to receive thefrusto-cones of said mounting elements, interposed between thejuxtaposed mounting elements and bonded thereto to form connector meansadapted to secure said one portion of said leg to said other portion.

8. A linkage for joining the shank portion of an articial leg to thethigh portion, comprising a tubular column extending from the upper endof said shank portion, said tubular column having a cylindrical blockremovably mounted thereupon, said thigh portion having its lower endsurrounding said cylindrical block, mounting elements secured to bothsides of said block, mounting elements secured to the interior of thelower end of said thigh portion contiguous to the mounting elements onsaid block and discs of resilient materia1 interposed between pairs ofopposed mounting elements and bonded thereto to form connector meansadapted to secure said shank portion to said thigh portion.

9. A linkage for joining the shank portion of an articial leg to thethigh portion, comprising a tubular column extending from the upper endof said shank portion, said tubular column having a cylindrical blockremovably secured thereupon, said thigh portion having its lower endsurrounding said cylindrical block, cylindrical, frusto-conical mountingelements secured to both sides of said block, cylindrical frusto-conicalmounting elements secured to the interior of the lower end of said thighportion contiguous to the mounting elements on said block and annulardiscs of resilient material having concave sides adapted to receive thefrusto-cones of said mountingelements interposed between the juxtaposedmounting elements and bonded thereto to form connector means adapted tosecure said shank portion to said thigh portion.

10. A knee joint for an artiiicial leg having a shank portion and athigh portion, comprising a tubular column extending upwardly from saidshank portion, a cylindrical block secured to said tubular column, aplurality oi V-grooves formed in the surface of said cylindrical block,mounting means secured to both sides of said cylindrical block, saidthigh portion having its lower end substantially surrounding saidcylindrical block, the lower end of said thigh portion having mountedthereupon V-shaped elements adapted to cooperate with the V-grooves insaid cylindrical block, mounting means secured to both sides ofthe'interior of the lower end of said thigh portion, and discs ofresilient material secured and bonded between said mounting means toform connectors adapted to secure said shank portion to said thighportion.

11. An ankle joint adapted to secure the foot portion of an articial legto the shank portion, said foot portion having a central well therein,comprising a tubular element having a necked down portion protrudingfrom said shank portion into said central v/ell in said foot portion,mounting means secured to the sides of said central well, mounting meanssecured to said necked down portion of said tubular element andresilient disc means interposed between and bonded to said mountingmeans to form a connection between said foot portion and said shankportion.

12. An ankle joint adapted to secure the foot portion of an artificialleg to the shank portion, said foot portion having a central welltherein` comprising a tubular element having a necked down portionprotruding from said shank portion into said central well in said footportion. mounting means secured to the sides of said central Well,mounting means secured to the sides of said necked down portion of saidtubular element, resilient disc means interposed between and bonded tosaid mounting means to form a connection between said foot portion andsaid shank portion and stop means secured about the periphery of saidtubular element to limit the movement of said foot means upon saidconnection.

13. An ankle joint adapted to secure the foot portion of an articial legto the shank portion, said foot portion having a central well therein.comprising a tubular element having a necked down portion protrudingfrom said shank portion into said foot portion, cylindricalfrusto-conical mounting means secured to the sides of said well in saidfoot portion, cylindrical, frusto-conical mounting means secured to saidnecked down portion of said tubular element and resilient disc meanshaving concave sides adapted to receive and be bonded to thefrusto-cones of said mounting means to form a connection between saidGLENN G. HAVENS.

No lreferences cited.

